Up to 1980 humanized mice will be used to determine the ability of passive or AAV mediated delivery of 4 different bnAbs to control HIV-1 infection. The VRC will provide the sequences for each of the 4 bnAb heavy and light chains as well as the proteins for use in the passive therapy experiments to the Subcontractor. The objectives of the Statement of Work (SOW) are to: 1/Measure the in vitro neutralization potential of 4 different bnAbs for a tier two isolate (REJO.c), a tier three isolate (TRJO.c), and an outgrown virus from a chronically infected patient. 2/ Determine the concentrations of each antibody necessary to control established HIV replication in the humanized mice model when infected with each of the above HIV-1 strains. 3/ Determine the effect of combinations of these bnAbs on controlling HIV infection in the humanized mice model. 4/ Sequence escape mutations that arise after treatment with either N6, 10E8, PGT121, and PDGM1400 or their combinations in humanized mice. 5/ Test the sensitivity of all of the above mutant viruses to a panel of bNAbs including N6, 10E8, PGT121, and PDGM1400 in vitro.